1. Field of the Disclosure
The present application relates to an apparatus for separating dirt or dust particles from an air flow by cyclonic means. The application relates particularly, but not exclusively, to a cyclonic dust separation apparatus for use in a vacuum cleaner.
2. Related Art
Cyclone dust separation devices typically include a frusto-conical (truncated cone) cyclone having a tangential air inlet at the one end having a large diameter and a cone opening leading to a dirt or dust collection area at the other end which has a smaller diameter.
There are numerous patents describing a variety of bagless vacuum cleaners now on the market by manufacturers such as Dyson, Hoover, Bissell; i.e. U.S. Pat. Nos. 5,858,038; 5,062,870; 5,090,976; 5,145,499; 6,261,330 and 5,853, 440; English Patent Pub. No. GB727137; and French Patent Pub. No. FR1077243.
U.S. Pat. No. 6,261,330 discloses a device including a fan for causing fluid to flow through the cyclone separator, the cyclone separator having an inlet and an interior wall having a frusto-conical portion tapering away from the inlet, wherein the fan is positioned in the inlet to the cyclone separator chamber on the same axis thereof, such that fluid passing through the fan is accelerated towards the interior wall, and thereby, given sufficient tangential velocity to cause cyclonic separation of particles from the fluid flow within the cyclonic separator chamber. The fan motor is located on the centerline of the cyclone separator chamber, and thus, adds to the size of the cyclone separator chamber.
In U.S. Pat. No. 6,261,330, the inlet port arrangement and the concentric exit port connectors to the cyclone separator are not optimum. The cyclone chamber depends on gravity to keep the dirt in the bottom of the collection chamber, thus requiring the suggested alternate configuration in which the motor is connected to the fan by a long shaft that extends through the cyclone chamber to the fan at the top of the chamber. This position is not ideal for providing suction to lift dirt from the floor. The patent contends that this is an advantageous design because it lowers the center of gravity of the device as a whole when compared to the embodiment shown with the motor at the top of the vertical cyclone separation chamber.
Since many standard vacuum cleaner motors now run at very high RPM's (22,000 RPM, for example) they provide good airflow and vacuum performance with reduced weight. Having a long shaft through the cyclone separator chamber, however, as suggested by the referenced patent, would not be ideal since shaft critical speed vibration problems are likely to result, thus preventing any weight reduction options to improve the desirability of the vacuum cleaner for the public use.
All of the cyclonic separator type vacuum cleaners now on the market have their cyclone separator chamber on the suction side of the fan so that they are driven by the air flow that is being sucked through them. This has the advantage of only clean air being pulled through the fan impeller, but provides much less velocity and energy than would be available by placing the cyclone separation chamber on the discharge side of the vacuum fan.
Accordingly, it would be desirable to provide a cyclonic dust separation device, preferably suitable for use in a home vacuum cleaner that avoids the problems discussed above.